JP3507638B2 - Thyristor type pulse discharge circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for generating a large current having a high efficiency and a high repetition frequency and a fast rising time, and in particular, a thyristor, a saturable reactor and a capacitor are connected in series, and a large current is generated by turning on the thyristor. The present invention relates to a thyristor type pulse discharge circuit for generating.

[0002]

2. Description of the Related Art Recently, a pulsed large current is used to excite a gas laser and form a pulsed magnetic field.
There is an increasing industrial demand for so-called pulse power technology. As a method of obtaining a large pulse current, a method of rapidly discharging a capacitor charged to a high voltage through a switch is generally used. In this type of circuit, conventionally, a thyratron in which low-pressure hydrogen gas or the like is enclosed is often used as a switch. However, since the thyratron is accompanied by discharge in the switching process, the consumption of the electrodes cannot be avoided, and therefore, there is a disadvantage that the life of the switch element is short and it is difficult to apply the pulse generator to a high repetition rate pulse generator. In order to solve this inconvenience, recently, an attempt has been made to perform a switching operation by a semiconductor element such as a thyristor that does not accompany switching with discharging.

FIG. 10 shows an average current capacity of 300 A to 50
As a conventional example of a pulse discharge circuit using a 0 A thyristor, the one disclosed in Japanese Patent Application Laid-Open No. 5-36550 is exemplified. This pulse discharge circuit includes a saturable reactor S for a capacitor C ₀ that functions as a power source.
L _A , a plurality of serially connected thyristors THY1, THY
2, ..., THYn (these are collectively referred to as “THY”),
And a capacitor C ₁ are connected in series to form a series resonance main circuit, and a load Z _L is connected in parallel to the capacitor C ₁ . The capacitor C ₀ is charged in advance to a predetermined high voltage by the charging power source HV, and the thyristor THY is turned on, that is, switched on. This allows the thyristor T
The terminal voltage of HY gradually decreases from the voltage V _0, and the terminal voltage V _SLA of the saturable reactor SL _A that was initially zero gradually increases. At this time, the saturable reactor SL _A has a high impedance in the initial non-saturation state, and only a small amount of circuit current flows. However, the saturable reactor SL _A increased magnetic flux density in proportion to the time integral value of the voltage, it impedance suddenly decreases shifts to saturation and reaches a predetermined value, the capacitor C ₀ is the series resonance main circuit Saturable reactor SL _A and capacitor C ₁
Through a discharge in the form of a pulsed current to charge the capacitor C ₁ . A pulse current is supplied to the load Z _L by the charging voltage of the capacitor C ₁ .

In the circuit shown in FIG. 10, the saturable reactor SL _A is inserted in the series resonance main circuit to suppress the current increase rate (the positive time differential value of the current) of the thyristor THY at the beginning of the current flow. The thyristor THY is designed to reduce the loss of the thyristor by compensating for the insufficient withstand current increase rate of the thyristor so that the thyristor having a relatively small capacity can be used for a pulse power application having a relatively large capacity.

However, this conventional pulse discharge circuit has a drawback that the loss of the thyristor cannot be sufficiently reduced even when the magnetic assist operation is performed by the saturable reactor SL _A.

[0006]

In order to eliminate this drawback, in the discharge circuit of Japanese Patent Laid-Open No. 5-36550, it is proposed to increase the leakage current of the saturable reactor when it is not saturated to some extent. However, in that method, if the leakage current is further increased in order to further reduce the loss of the thyristor and increase the current increase rate withstand capability, the initial charge is discharged as a leakage current and transmitted to the core load Z _L. There is an inconvenience that the pulse current becomes small.

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional pulse discharge circuit, and reduces the voltage drop of the thyristor when the pulse current starts to flow,
An object is to provide a highly efficient and low loss thyristor type pulse discharge circuit.

[0008]

In order to achieve the above object, the invention of claim 1 is characterized in that the first capacitor, which is charged in advance, is turned on by turning on the thyristor.
In a magnetically-assisted thyristor-type pulse discharge circuit that obtains a pulse current by discharging through a saturable reactor, a series resonance consisting of a reactor and a second capacitor is used to control the saturation point of the first saturable reactor. It is characterized in that the circuit is connected in parallel to the thyristor.

According to a second aspect of the present invention, in the thyristor type pulse discharge circuit according to the first aspect, a braking resistor is connected to the series resonance circuit.

According to a third aspect of the present invention, in the thyristor type pulse discharge circuit according to the first or second aspect, the reactor of the series resonance circuit is configured as a second saturable reactor, and after the thyristor is turned on, The time until saturation of the first saturable reactor is D _t1 , the time until saturation of the second saturable reactor is D _t2 , the increase rate of the current flowing through the first saturable reactor is I ₁ ′, the second Assuming that the rate of increase of the current flowing through the saturable reactor of I ₂ ′ is D _t1
It is characterized in that the circuit constants are set so that> D _t2 and I ₁ ′> I ₂ ′.

According to a fourth aspect of the invention, in the thyristor type pulse discharge circuit according to the third aspect, the iron core material of the second saturable reactor is ferrite.

According to a fifth aspect of the present invention, in the thyristor type pulse discharge circuit according to the third or fourth aspect,
It is characterized in that a resistor is connected in parallel with the saturable reactor of.

According to a sixth aspect of the present invention, in the thyristor type pulse discharge circuit according to any one of the first to fifth aspects, a diode is connected in parallel with a reactor of an LC series circuit connected in parallel with the thyristor. It is characterized by.

According to a seventh aspect of the present invention, in the thyristor type pulse discharge circuit according to any of the first to sixth aspects, the thyristor is a high speed thyristor having a distributed gate structure. .

According to an eighth aspect of the invention, in the thyristor type pulse discharge circuit according to any one of the first to sixth aspects, the thyristor is a gate turn-off thyristor.

According to a ninth aspect of the present invention, in the thyristor type pulse discharge circuit according to any of the first to eighth aspects, the thyristor is composed of a pressure contact type flat thyristor, and the flat thyristor is provided on the outer peripheral side. An iron core made of a toroidal ferromagnetic material is arranged to form the first saturable reactor, discoid conductors are arranged on both end faces of the iron core, and a first capacitor is arranged on the outer peripheral side of the iron core. It is characterized in that a plurality of them are distributed in the direction.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) (Structure): FIG. 1 is a connection diagram of an embodiment of a thyristor type pulse discharge circuit according to claim 1 of the present invention, and FIG. 2 is a waveform for explaining its operation. It is a figure. In the pulse discharge circuit of FIG. 1, a series resonant circuit LC including a reactor L _PA and a capacitor C _PA is connected in parallel to the thyristor THY. The other circuit parts are the same as the circuit of FIG. The capacitor C ₀ , the saturable reactor SL _A and the capacitor C ₁ constitute a series resonant main circuit, and the series resonant circuit LC including the reactor L _PA and the capacitor C _PA.
Constitutes a series resonance auxiliary circuit. Thyristor THY
Serves as a switch that determines when the charged capacitor C ₁ is discharged through the load Z _L. The load Z _L is connected in parallel with the capacitor C ₁ .

(Operation): Initially, both the capacitor C ₀ and the capacitor C _PA are almost at the voltage V ₀ by the charging power source HV.
Although the thyristor THY is charged, the thyristor THY maintains the charged state without being discharged as long as it is in the off state. Figure 2
At time t ₀ , when the thyristor THY is turned on (switched on), the terminal voltage V _THY of the thyristor _THY starts to drop from the initial voltage V ₀ , and accordingly the terminal voltage V _SLA of the saturable reactor SL _A is increased. As the voltage starts to rise, the series resonance auxiliary circuit LC including the reactor L _PA and the capacitor C _PA connected in parallel to the thyristor THY also starts to discharge, and the current I
_RES begins to flow. In this state, the saturable reactor SL _A is still in a non-saturated state, so that the inductance value is large and the current I from the capacitor C ₀ flows only slightly, but the current I _RES of the resonance auxiliary circuit gradually increases. When the current I _RES reaches the peak value, the saturable reactor SL _A is just saturated and its inductance value is rapidly reduced. As a result, a large pulse current I flows in the series resonant main circuit composed of the capacitor C ₀ , the saturable reactor SL _A and the capacitor C ₁ , and the capacitor C ₁ is charged. The charging voltage causes discharging to the load Z _L.

(Effect): In this way, during the magnetic assist period by the saturable reactor SL _A , the current I _RES from the series resonance auxiliary circuit LC supplies the carrier to the thyristor THY in place of the leakage current of the saturable reactor SL _A. However, the inside of the thyristor element can be filled with the carrier. Therefore, when the main circuit current starts to flow after the end of the magnetic assist period, the on-resistance of the thyristor THY is sufficiently reduced, and the loss of the thyristor can be reduced. Moreover, since it is not necessary to intentionally use a saturable reactor SL _A having a large leakage current, the loss of the saturable reactor SL _A can be reduced. As an iron core material of the saturable reactor SL _{A having} a small leakage current, for example, a cobalt-based amorphous iron core is suitable.

In the first embodiment, when the damping resistor is inserted in the series resonance auxiliary circuit LC as described in claim 2, the current waveform of the series resonance auxiliary circuit LC can be made into a non-oscillating single pulse. . The reason is that if an oscillating pulse current continues to flow in the thyristor THY, the turn-off characteristic of the thyristor is hindered, so this is more convenient for using the pulse discharge circuit at high repetition rates. .

(Second Embodiment) (Structure): FIG. 3 is a diagram showing the structure of a third embodiment of the present invention. FIG. 2 corresponds to the reactor L _PA of the series resonance auxiliary circuit LC in the first embodiment of FIG. 1 replaced with a saturable reactor SL _PA . 4 and 5 are diagrams for explaining the operation.

(Operation): The description of the parts common to the first embodiment is omitted, and only the parts unique to the present embodiment will be described. Thyristor T at time t ₀
When HY turns on, the saturable reactor S of the main circuit
Saturable reactor SL _{PA of} L _A and series resonance auxiliary circuit LC
Since both are in a non-saturated state, only leakage current of the saturable reactor flows through the thyristor THY. When the saturable reactor SL _PA of the series resonance auxiliary circuit LC is saturated at time t ₁ after a lapse of time D _t1, the current I _RES of the series resonance auxiliary circuit LC rapidly increases. Furthermore, time t ₂
Then, when the current I _RES of the series resonance auxiliary circuit LC reaches the peak value, the saturable reactor SL _A of the main circuit is also saturated, and the main circuit composed of the capacitor C ₀ , the saturable reactor SL _A and the capacitor C ₁ is large. Pulsed current I
Will flow. During this time, the total current I ₀ flowing through the thyristor THY changes with a waveform as shown in FIG.

(Effect): In this way, during the magnetic assist period by the saturable reactor SL _A , from time t ₀ to t.
Up to ₁ saturable reactor SL _A and saturable reactor S
Leakage currents from both L _PA supply carriers to the thyristor THY. In this way, the saturable reactor SL _PA becomes saturated when carriers are filled to some extent inside the element,
A larger amount of carriers is supplied from the series resonance auxiliary circuit LC. Then, the amount of carriers inside the element becomes sufficient, and at time t ₂ when the ON resistance of the element decreases, the saturable reactor SL _A of the main circuit is saturated and the main circuit current flows. As described above, in the second embodiment, the supply of carriers is performed in two stages of the leakage current of the saturable reactor SL _A and the resonance current of the series resonance auxiliary circuit LC, and therefore, the leakage current of the saturable reactor C ₀ . Is a low increase rate I ₁ ′ in a period when the ON region of the thyristor THY is not sufficient, and the resonance current of the series resonance auxiliary circuit LC is a medium current change rate I ₂ ′ after the ON region of the thyristor THY is expanded to some extent. It has the advantage that it can be optimized for the operating state of the thyristor THY.

As a characteristic of the saturable reactor SL _PA of the series resonance auxiliary circuit LC, it is preferable that the saturable reactor SL _PA has a soft switching characteristic in which the current gradually increases rather than abruptly changing from an unsaturated state to a saturated state. It is desirable to reduce the switching loss of the thyristor THY. Such a characteristic is an iron core of the saturable reactor SL _PA.
It can be realized by using a ferrite (for example, a ferrite such as PE-1 material manufactured by TDK Corporation) as described in 1.

(Third Embodiment) FIG. 6 is a block diagram showing a fifth embodiment of the present invention. In this embodiment, a resistor R _PA is connected in parallel with the saturable reactor SL _PA shown in FIG. FIG. 7 is a diagram for explaining the operation.

(Operation): When the thyristor THY turns on at time t ₀ , both the saturable reactor SL _A of the main circuit and the saturable reactor SL _PA of the series resonance auxiliary circuit LC are in a non-saturated state, so that the thyristor THY is turned on. The leakage current of the saturable reactor is resistance R _PA and capacitor C
_Flow through _PA . The current passing through the resistor R _PA begins to flow simultaneously with the turn-on of the thyristor THY and reaches its peak immediately, after which the current follows the discharge time constant given by the product of the capacitance of the capacitor C _PA and the resistance value of the resistor R _PA. Decay. The operation after the time t ₁ is the same as that of the second embodiment.

(Effect): In this way, during the magnetic assist period by the saturable reactor SL _A , from time t ₀ to t.
Up to ₁ saturable reactor SL _A and saturable reactor S
In addition to the leakage current from L _PA , the current discharged through the resistor R _PA supplies carriers to the thyristor THY. Therefore, even if the leakage current of the saturable reactor SL _A is reduced, the thyristor can be filled with carriers and the on-resistance can be sufficiently reduced. In the conventional pulse discharge circuit, the saturable reactor S is used to supply the carrier to the thyristor THY.
An iron core having a relatively large leakage current was used for L _A , but this caused an increase in iron core loss. According to the present invention, even if the saturable reactor SL _A has low leakage current and low loss, the thyristor loss can be reduced and the efficiency can be improved.

(Fourth Embodiment) (Structure): FIG. 8 shows a sixth embodiment of the present invention. In this embodiment, n sets (n is an integer of 2 or more) of thyristors THY (1), THY (2), ..., THY.
(n) are connected in series, and each thyristor has a braking resistor R _S , a saturable reactor SL _PA , a capacitor C _PA ,
And series resonance auxiliary circuit LC including diode D _S
1, LC2, ..., LCn are connected in parallel,
The diodes D _R (1), D _R (2), ..., D _R (n) are connected in antiparallel. In the series resonance auxiliary circuit LC, the braking resistor R _S , the saturable reactor SL _PA and the capacitor C _PA are connected in series, and the diode D _S is connected in parallel to the braking resistor R _S and the saturable reactor SL _PA . Has been done.

(Operation): With such a configuration, the following operation and effect are produced as compared with the case where the diode D _S is not connected to the series resonance auxiliary circuits LC1, LC2, ..., LCn. That is, initially, when the capacitor C ₀ is charged, the transient shared voltage of the plurality of thyristors connected in series is the impedance of the impedance element connected in parallel to each element, for example, in the pulse discharge circuit of FIG. For example, it is determined by the inductance of the reactor L _PA and the capacitance of the capacitor C _PA for each element. The distribution of the shared voltage for each element is affected by a stray capacitance that does not appear in the circuit diagram, and thus generally does not become an ideal distribution, that is, a distribution state in which all the elements have a uniform shared voltage. In order to reduce the adverse effect of this stray capacitance, it is effective to connect the capacitance in parallel with the element. Therefore, when the diode D _S is not provided in the discharge circuit of FIG. 8, the saturable reactor SL _PA connected in series with the capacitor C _PA cuts off the high frequency component of the charging current, so that the capacitor C _PA has a shared voltage. Since it is not effective as a capacitance for improving, it is necessary to connect another capacitor, which increases charging energy and reduces efficiency. On the other hand, by connecting the diode D _S , the charging current flows by bypassing the saturable reactor SL _PA , and the capacitor C _PA effectively acts also as a capacitance for improving the shared voltage. Therefore, the capacitance of the capacitor connected to the circuit can be reduced, and the efficiency can be improved.

(Other Embodiments) In the present invention, the saturable reactor is used to limit the current in the main circuit from flowing until the thyristor is turned on and the on-resistance is lowered to some extent. As this period is shorter, the saturable reactor can be made smaller and lighter, and a thyristor type pulse discharge circuit with low loss can be obtained. for that purpose,
As described in claim 7, a high speed thyristor having a distributed gate structure excellent in gate control ability may be used as the thyristor. Further, when a gate turn-off thyristor having a better gate control capability is used as the thyristor, it is possible to achieve a small size, light weight, and low loss.

FIG. 9 is a structural diagram showing an embodiment of a thyristor type pulse discharge circuit according to a ninth aspect of the invention, and corresponds in circuit form to the pulse discharge circuit of FIG. The flat thyristor 10 has radiators 11A and 11B from both sides thereof.
It is clamped and fixed on the base 15 by the clamping members 17A and 17B with the insulating plate 12 and the clamp 13 interposed therebetween. A pair of disk-shaped conductors 20A and 20B are fixed to the radiators 11A and 11B, and a plurality of sets of capacitors C ₀ and C ₁ are attached in pairs in the circumferential direction so as to be dispersed in pairs. In addition, the conductors 20A, 20
In the space sandwiched by B, a doughnut-shaped iron core 21 formed by winding an amorphous ribbon in a toroidal shape is arranged concentrically with the thyristor 10. Furthermore, the conductors 20A, 20
Capacitors C ₀ and C ₁ are connected to B by an insulating lead wire 24, and a reactor SL _PA and a capacitor C _{PA of} the series resonance auxiliary circuit LC are connected by an insulating lead wire 25. When configured as in this embodiment,
The toroidal iron core 21 and the current loops above, below, inside and outside thereof form a saturable reactor SL _A having a winding number of 1 and the circuit is completely equivalent to the circuit of FIG.

The inductance L _TR of the toroidal coil in the pulse discharge circuit of FIG. 9 is given by L _TR = μN ² S / (2πa) (1) Here, μ is the permeability, N is the number of turns, a is the average radius of the coil, and S is the coil cross-sectional area.

In the saturable reactor used for magnetic assist, the cross-sectional area S is automatically determined when the assist time is determined. Therefore, in order to reduce the inductance and increase the current increase rate, the coil is calculated from the equation (1). It can be seen that it is desirable to increase the average radius of to increase the magnetic path length.
According to this embodiment, since the iron core 21 is arranged on the outer peripheral side of the thyristor 10, the coil radius can be increased and a thyristor type pulse discharge circuit with a large current increase rate can be obtained.

[0035]

As described above, according to the present invention, it is possible to obtain a thyristor type pulse discharge circuit having a low loss and a high efficiency by reducing the voltage drop of the thyristor.

[Brief description of drawings]

FIG. 1 is a connection diagram of a thyristor type pulse discharge circuit according to claim 1 of the present invention.

FIG. 2 is a diagram for explaining the operation of the pulse discharge circuit of FIG.

FIG. 3 is a connection diagram of a thyristor type pulse discharge circuit according to claim 3 of the present invention.

FIG. 4 is a diagram for explaining the operation of the pulse discharge circuit of FIG.

5 is a diagram for explaining the operation of the pulse discharge circuit of FIG.

FIG. 6 is a connection diagram of a thyristor type pulse discharge circuit according to claim 5 of the present invention.

FIG. 7 is a diagram for explaining the operation of the pulse discharge circuit of FIG.

FIG. 8 is a connection diagram of a thyristor type pulse discharge circuit according to claim 6 of the present invention.

FIG. 9 is a side view in which a part of the thyristor type pulse discharge circuit according to the present invention is cut away.

FIG. 10 is a connection diagram of a conventional thyristor type pulse discharge circuit.

[Explanation of symbols]

THY thyristors THY1 to THYn thyristors LC series resonance auxiliary circuits LC1 to LCn series resonance auxiliary circuits C ₀ and C ₁ capacitors SL _A and SL _PA saturable reactor L _PA reactor R _PA resistance C _PA capacitors D _s and D _R (1) to D _R (n) Diode R _s Resistor 10 Thyristor 11A, 11B Radiator 12 Insulation plate 13 Clamp 20A, 20B Conductor 21 Iron core

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-36550 (JP, A) JP-A-56-91680 (JP, A) JP-B-52-28626 (JP, B2) JP-B-51- 9262 (JP, B1) S. 52-26838 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 9/04 H01F 29/14 H03K 3/45

Claims (9)

(57) [Claims] 1. A first capacitor, which is precharged,
In a magnetically-assisted thyristor-type pulse discharge circuit in which a thyristor is turned on to discharge through a first saturable reactor to obtain a pulse current, in order to control the saturation point of the first saturable reactor,
A thyristor type pulse discharge circuit in which a series resonance circuit including a reactor and a second capacitor is connected in parallel to the thyristor. 2. The thyristor type pulse discharge circuit according to claim 1, wherein a braking resistor is connected to the series resonance circuit. 3. The thyristor type pulse discharge circuit according to claim 1, wherein the reactor of the series resonant circuit is configured as a second saturable reactor, and the first saturable circuit is turned on after the thyristor is turned on. The time until the reactor is saturated is D _t1 , the time until the second saturable reactor is saturated is D _t2 , the increase rate of the current flowing through the first saturable reactor is I ₁ ′, the second Assuming that the rate of increase of the current flowing through the saturable reactor is I ₂ ′, D _t1
A thyristor type pulse discharge circuit having circuit constants set such that> D _t2 and I ₁ ′> I ₂ ′. 4. The thyristor type pulse discharge circuit according to claim 3, wherein the iron core material of the second saturable reactor is ferrite. 5. The thyristor type pulse discharge circuit according to claim 3 or 4, wherein a resistor is connected in parallel with the second saturable reactor. 6. The thyristor type pulse discharge circuit according to claim 1, wherein a diode is connected in parallel with a reactor of the series resonance circuit connected in parallel with the thyristor. Thyristor type pulse discharge circuit. 7. The thyristor type pulse discharge circuit according to claim 1, wherein the thyristor is a high speed thyristor having a distributed gate structure. 8. The thyristor type pulse discharge circuit according to claim 1, wherein the thyristor is a gate turn-off thyristor. 9. The thyristor type pulse discharge circuit according to claim 1, wherein the thyristor comprises a pressure contact type flat thyristor, and the first thyristor is provided on the outer peripheral side of the flat thyristor. In order to form a saturable reactor, an iron core made of a toroidal ferromagnetic material is arranged, and disk-shaped conductors are arranged on both end faces of the iron core.
The thyristor type pulse discharge circuit is characterized in that a plurality of the first capacitors are dispersed in the circumferential direction on the outer peripheral side of the iron core.